Nanoscale One-and Two-Dimensional Nuclear Magnetic Resonance Spectroscopy Based On Nitrogen-Vacancy Center In Diamond

Nuclear magnetic resonance(NMR)is a promising technique for molecular structure analysis and plays an important role in biology,medicine,physics,and materials chemistry.Compared with X-ray crystal diffraction techniques and electron microscopy,NMR is a promising technique to reveal the structural information with fast and nondestructive in vivo detection at room temperature.With the deeper understanding of the micro-world,it is necessary to develop more high-precision and highsensitivity method to explore the structural information of matter at nanoscale or even at single molecule level.However,traditional NMR requires billions of molecules to obtain the signal-to-noise ratio,and other existing single-molecule probing methods cannot achieve nondestructive situ measurements.Advancing the sensitivity and resolution of NMR to the single-molecule level has always been an important and hot spot in this field.The nitrogen vacancy(NV)center in diamond,however,is a very suitable spin sensor for nano-even single-molecule NMR,which can perform highly sensitive magnetic detection at room temperature.In this thesis,we built an experimental ODMR platform and used it for the nanoscale molecular structure analysis.The following works are related.1.Detection of magnetic dipole interactions is an important of nanoscale NMR.we observed the liquid and solid state NMR 1D spectra of(6 nm)3 water molecules on diamond surfaces,detected the dipole coupling interactions between the internal protons of water molecules in nano ice crystal by correlation spectroscopy methods,and resolved the azimuthal information of the ice crystals.By varying the temperature,we also detected the phase transition of water molecules on the diamond surface.2.Nano-2D NMR spectroscopy is one of the key techniques for performing single molecule structure analysis.Analogous to the COSY spectroscopy in conventional NMR,we develop a two-dimensional correlation spectral sequence based on the NV color center,and got a nano-2D NMR spectrum of a pair of 13C nuclear spins.From the spectrum,we obtained the bond length between two 13C atoms and the precise position of this nuclear spin pair by spectroscopic analysis.Furthermore,a non-periodical multinuclear species correlation sequence is introduced,which can simultaneously observe multiple nuclear spins and the coupling between them,and achieved atomic-level resolution for structure resolution theoretically.3.In the previous work,the detection of 2D nano-NMR spectra is typically consumes days of time,so we applied an artificial intelligence method to the data processing and analysis of 2D NMR spectra.Training deep learning neural network by simulation data and combining with matrix filling method can greatly improve the efficiency of the experiment,with a 5.7 dB improvement in SNR even at 10%reduced sampling rate.4.Carrying out other applications related to microscopic NMR,we prepared quantum atmospheres with time-reversal symmetry conservation and breaking states of single-nucleus spins and successfully observed their symmetries.This work demonstrates in principle that the search for symmetry patterns from quantum atmospheres is conceptually feasible and opens up completely new possibilities for potential applications of quantum precision measurements in materials diagnostics.